Log adjusting and aligning device

ABSTRACT

At a sawmill a device at the input side of the sawmill for adjusting automatically a log or a similar elongated object to be sawn relative to the center line or sawing line through the sawing unit so that a straight line through the centers of the end surfaces of the log becomes parallel to and coincident with the sawing line, if the log is straight, but parallel to and transversely offset from the sawing line, if the log is curved or bent, said transverse offset having a direction opposite to the direction of the curve or bow in the log and a magnitude which is a predetermined proportion of the height of the curve or bow in the log.

United States Patent t Ackerfeldt [45] May 30, 1972 [541 LOG ADJUSTING AND ALIGNING 557,813 4/1896 Hadgrave 143/157 R DEVICE 2,904,083 9/ 1959 Mater 143/ 122 [72] inventor: nu lngemu Ackerman, stockholm, FOREIGN PATENTS 0R APPUCATTONS Swede 827,545 1/1952 Germany 143/75 A 73 A' :USNRFrestldustrieslQPrtl d, l Sslgnee ores o n ne o an Primary Examiner-Donald R. Schran Attorney-Buckhom, Blore, Klarquist and Sparkman [22] Filed: Aug. 19, 1970 [2l] Appl. No.: 65,005 [57] ABSTRACT v At a sawmill a device at the input side of the sawmill for ad- Relat/ed U.S. Application Data justing automatically a log or a similar elongated object to be sawn relative to the center line or sawing line through the saw- [63] Commuaton of ser No' 779102 Nov' 26 1968 ing unit so that a straight line through the centers of the end abandone surfaces of the log becomes parallel to and coincident with the sawing line, if the log is straight, but parallel to and transverse- [52] US Cl' 143/157 R ly o'set from the sawing line, if the log is curved or bent, said [5 l] Int. CI ..B27b 31/06 transverse offset having a direction Opposite to the direction [58] Field 0f Sardi 143/157 R, 122, 75 A, 3l, 56; of the curve or bow in the log and a magnitude which is a 83/360, 367 predetermined proportion of the height of the curve or bow in the log. [56] References Cited 25 Claims, 7 Drawing Figures UNITED STATES PATENTS 115,903 6/1871 stems.... 143/1272 Patented May 30, 1972 6 Sheets-Sheet l Patented May 30, 1972 6 Sheets-Sheet 2 N OT..

Patented May 30, 1972 3,665,984

6 Sheets-Sheet 3 FIG 3 Patented May 30, 1972 6 Sheets-Sheet 4 e NW@ mw mw mm @N mm Patfanted May 30, 1972 6 Sheets-Sheet 5 Patented May 30, 1972 3,665,984

6 Sheets-Sheet 6 FIGB LGG ADJUSTING AND ALIGNING DEVICE This application is a continuation of my co-pending application Ser. No. 779,102, filed Nov. 26, 1968, for Device at a Sawmillfor Adjusting a Log to be Sawn Relative to the Sawing Line through the Sawing Unit, now abandoned.

This invention relates to a device at a sawmill -for aligning and adjusting a log or a similar elongated item to be Sawn relative to the center line through the sawing unit, the so-called sawing line, with automatic compensation for any curve or bow in the log. v t

- When cutting logs into boards and similar products the logs are generally rst passed through a double cant saw, in which two side cuts are made along opposite sides of the logs, wherebylogs with two opposite plane sides, so-called cants are obtained. These cant-Sawn logs or cants are then cut in a sawmill with one or several saw blades, in which the cuts through the logs are made perpendicularlyto the two opposite plane sides of the logs. At the first cant-sawing of the original logs,these are generally adjusted in such a way relative to the saw that any curve or bow in the logs lies in a plane parallel to the cuts made through the logs, that is,to the opposite plane sides of the logs running after the cant-sawing. When thereafter these logs are fed into a saw to be cut along planes perpendicularto the plane sides of the logs, the logs must be adjusted as accurately as possiblerelative to the center line, the so-called sawing line, through the sawmill. l-litherto the logs have generally been adjusted by hand by a sawmill operatorlocated at the input side of the saw. Recently, also automatically operating devices for adjusting and aligning the logs relative to the sawing line through the saw have been used. If the log is completely straight, it shall be adjusted in such a way that a straight line through the centers ofthe two end surfaces of the log coincides with the sawing line through the saw. lf,

however, the log is curved or bent, such a position of the log relative to the sawing line will not give an optimum yield from the log. Instead a curved log should be so positioned and adjusted relative to the sawingv line through the saw that a straight line through the centers of the two end surfaces of the log is certainly parallel to the sawing line through the saw but transversely offset relative to this in the direction opposite to the bow of the log. ln general, it is 'considered that the cutting of a curved log into boards and similar products will give an optimal yield, if the straight line through the centers of the `end surfaces of the log is transversely oset from the Asawing line through the saw by a distance corresponding to one-half of the so-called height" of the bow in the log. The height of the bow means,in this case,the largest distance between the straight line through the centers of the two end surfaces of the log and the curved center line through the log. Manual adjustment of the log with correct compensation for any bow in the log requires great skill of the sawmill operator and becomes increasingly more difficult to achieve with satisfactory accuracy when the speed of operation of the sawmill is increased. Previously used devices for automatically adjusting and aligning logs at the input side of a sawmill do not give a satisfactory compensation for a curve or bow in the logs.

y Therefore, the principal object ofthe present invention is to provide an automatically operating device for adjusting and aligning logs or similar elongated items to be sawn in a sawmill relative to the sawing line through the sawmill with automatic and correct regard to and compensation for any curve or bow in the logs. f

The device according to the invention includes three gripping devices carried by a carriage or a system of carriages and disposed one after the other in the direction of the sawing line through the sawmill. Each gripping device comprises two gripping arms or levers which are symmetrically movable to and from each other and arranged to touch opposite sides of a log positioned between them. The two outer gripping devices, that is,the foremost and the rearmost gripping devices, are mounted on the carriage or system of carriages so as to grasp a log adjacent its fore end and rear end, respectively, and so that the connecting line between these two gripping devices is parallel to the sawing line through the sawmill. F urther, these two gripping devices are unmovable with respect to the carriage means in the direction perpendicular to the vertical plane through their mutual connecting line. When these two gripping devices grasp a log at its fore and rear ends, respectively, the log is consequently automatically adjusted so that a straight line through the centers of the two end surfaces of the log becomes parallel to the sawing line through the saw. The third gripping device is located between the two above-mentioned gripping devices, as for instance halfway between them, and is mounted on the carriage system so as to be movable or displaceable relative to this in the direction perpendicular to the vertical plane through the connecting line between the two outer gripping devices. This third gripping device will consequently be moved or displaced transversely.' relative to the carriage system in proportion to any curve or bow in the log which is grasped at its fore and rear ends by the two outer gripping devices. The magnitude and the direction of the displacement of said third gripping device from the vertical plane through the connecting line between the two outer gripping devices will obviously correspond to the magnitude and the direction of the curve or bow in the log. The said third gripping device is connected or coupled to a bow-indicating member, which is carried by the carriage system and is displaceable in response to the transverse displacement of said third gripping device in the direction perpendicular to said vertical plane in such a way that'the displacement of the bowindicating member from its neutral position is in a sense identical to and in magnitude a predetermined proportion, as for instance one-half, of the transverse displacement of said third gripping device from a vertical plane through the connecting line between the two outer gripping devices located at the ends of the log. If the log is completely straight, the bowindicating member remains consequently in its neutral position. If, however, the log is curved or bent to the right, the bow-indicating member is displaced to the right from its neutral position by an amount'corresponding to a predeter-- mined proportion ofthe height of the bow in the log. If instead the log is curved to the left, the bow-indicating member is in the similar way displaced to the left from its neutral position. The carriage system carrying the gripping devices can be moved by driving means in such a way that the vertical plane through the connecting line between the two outer gripping devices remains substantially parallel to the vertical plane through the sawing line of the sawmill but is moved in the direction perpendicular to said latter vertical plane, and the bow-indicating member on the caniage system is arranged to cooperate with stationary means for stopping the movement of the carriage system in a position determined by the position of the bow-indicating member relative to its neutral position. The stationary stopping means is so disposed relative to the vertical plane through the sawing line of the sawmill that with the bow-indicating member in its neutral position the carriage system is stopped with the vertical plane through the connecting line between the two outer gripping devices located at the ends of the log coinciding with the vertical plane through the sawing line. If, however, the bow-indicating member is displaced from its neutral position due to a curve or bow in the log grasped by the gripping devices, the carriage system is stopped in a position with the vertical plane through the connecting line between the two outer gripping devices and thus with the straight line through the centers of the end surfaces of the log transversely offset from the sawing line of the sawmill by a distance corresponding to the displacement of the bowindicating member from its neutral position. ln this way the log is automatically adjusted relative to the sawing line of the sawmill with correct regard to and compensation for any curve or bow in the log.

ln the following the invention will be further described with reference to the accompanying drawings, which by way of example show an embodiment of the invention.

FIG. l is a top view and FIG. 2 is a side view along the line ll-Il in FIG. 1 showing a sawmill with a device according to the invention for automatically adjusting logs to be sawn relative to the sawing line through the saw at the input sides of the saw; the device according to the invention being shown only schematically with broken lines;

FIG. 3 is a top view showing more in detail the adjusting device according to the invention;

FIG. 4 is a side view of the adjusting device shown in FIG. 3;

FIG. 5 is a sectional view of the adjusting device taken along line Va-Va in FIG. 3 and of the sawmill taken along line Vb-Vb in FIG. l;

FIG. 6 shows in an enlarged scale a suitable design of the lowermost ends of the gripping arms in the gripping devices as viewed in the direction parallel to a log grasped by the gripping device; and

FIG. 7 illustrates two possible positions of operation for such a gripping arm as viewed in a section taken along the line VII-VII in FIG. 6.

The sawmill shown in FIGS. 1 and 2 includes a sawing unit 1, as for instance a frame saw shown only schematically in the drawing. The center line or sawing line through the sawing unit 1 is designated by 2 and the feeding direction into the sawing unit is indicated by an arrow 3. For feeding logs to the saw 1,a conveyor generally designated by 4 is provided. The logs are supplied from a double cant saw 5 only schematically shown in the drawing. From this cant saw 5,the logs, which have been cut on two opposite sides in the saw 5, are transported in the direction indicated by an arrow 6 by means of a longitudinal conveyor generally designated by 7. On this conveyor the logs are stopped by a stop member 8. From the longitudinal conveyor the logs can be transferred to a transverse conveyor consisting of a number of conveyor chains 9. As schematically shown in FIG. 5, the outer ends of the conveyor chains 9 can be elevated or raised so that a log lying on the longitudinal conveyor 7 is lifted up from this and moved by the transverse conveyor 9 in the direction indicated by an arrow 10 in FIG. 1 to a number of support beams 11. A log resting on these support beams 11 close to the discharge end of the transverse conveyor 9 can be grasped by the adjusting device according to the invention, shown only schematically with broken lines in FIGS. l and 2 and generally designated by 12, and be moved by this transversely along the support beams l1 to the position designated by 12a in FIG. 1 above the input conveyor 4 to the saw 1 and in this position be adjusted correctly relative to the sawing line 2 through the saw 1 with regard to any curve or bow in the log. During this transverse displacement and adjustment of the log, it is continuously supported by the support beams 1 l. As can be seen in FIG. 5, the support beams are pivoted about one end from the horizontal position shown by solid lines in FIG. 5, in which position they can support a log spaced above the input conveyor 4 of the sawing unit l, and a slightly lower position shown by broken lines in FIG. 5. When by means of the adjusting device according to the invention the log has been correctly adjusted relative to the sawing line 2, the support beams l1 are lowered so that the adjusted log is put down onto the input conveyor 4 and is fed by this into the sawing unit 1. Simultaneously a clamping roller 13 may be pressed down against the upper plane side surface of the log so that the log is not moved out of its adjusted position when being fed into the sawing unit 1.

As shown in FIGS. 3 and 4, the adjusting device according to the invention, which is generally designated by 12, comprises an elongated, rectangular frame or carriage 14 provided with wheels l5 running along horizontal girders 16, which extend perpendicular to the sawing line 2 of the sawing unit l. The carriage 14 carries three dependent gripping devices 17, 18 and 19. The foremost gripping device 17 located closest to the sawing unit 1 is stationarily mounted on the carriage 14, whereas the middle gripping device 18 and the rearmost gripping device 19 are mounted on the lower side of carriages 20 and 2l, respectively, which are provided with wheels 20a and 21a running along the long sides of the carriage 14. The gripping devices 18 and 19 can consequently be moved in the longitudinal direction of the carriage 14 so that their positions can be adjusted to the length of the logs. The gripping device 17 is used for grasping the log adjacent its fore end, whereas the gripping device 19 grasps the log adjacent its rear end. In the illustrated embodiment of the invention the middle gripping device 18 is arranged to grasp the log at a point halfway between the two outer gripping devices 17 and 19. The carriages 20 and 21 carrying the gripping devices 18 and v19, respectively, are adjusted simultaneously in the longitudinal direction of the carriage 14 by means of an adjusting motor 22 mounted on the carriage 14. The motor is coupled to a shaft 24 through a driving chain 23. The shaft 24 is provided with two large sprocket wheels 25 over which endless driving chains 26 run. The driving chains 26 run also over sprocket wheels 27 mounted at the opposite end of the carriage 14 and are coupled to the carriage 2l for the rearmost gripping device 19. The shaft 24 is also provied with two smaller sprocket wheels 28, over which driving chains 29 run. The driving chains 29 run also over sprocket wheels 30 mounted on a shaft 31 journalled in the carriage 14 and are coupled to the carriage 20 for the middle gripping device 18. As the diameter of the sprocket wheels 28 is one-half of the diameter of the sprocket wheels 25, the adjusting motor 22 will move the carriage 20 of the gripping device 18 a distance which is one-half of the length of movement of the carriage 21 of the gripping device 19. Consequently, the gripping device 18 will always be located halfway between the outer gripping devices 17 and 19.

The gripping devices 17, 18 and 19 are to a large extent of identical design, wherefore it is sufficient to describe the middle gripping device 18, which is shown in detail in FIG. 5. This gripping device consists of a yoke 32 attached to the carriage 20 and two gripping arms 33 pivoted in the yoke. The gripping I arms 33 are provided with toothed segments 34 engaging one another so that the gripping arms 33 are always swung symmetrically relative to the symmetry plane 35 through the gripping device. From the raised position shown in solid lines in FIG. 5 the gripping arms 33 can be pivoted downwards by means of a hydraulic cylinder 36 to the position shown in broken lines, in which position the lowermost ends of the gripping arms are pressed by a certain force against opposite sides of a log 37 lying on the support beams 11. So far all the gripping devices 17, 18 and 19 are identical; the foremost gripping device 17 being, however, as mentioned in the foregoing, stationarily mounted on the carriage 14 so as to be unmovable thereto in the longitudinal direction as well as the transverse direction of the carriage 14. The rearmost gripping device 18 is in a similar way stationarily mounted on the carriage 21 so that it can be adjusted in the longitudinal direction of the carriage 14 as explained in the foregoing, but is unmovable in the transverse direction of the carriage 14. These two outer gripping devices 17 and 19 are so positioned or located relative to the carriage 14 that the connecting line 38 between them (see FIG. 3 and also FIG. 1) is parallel to the sawing line 2 through the sawing unit 1. Consequently, the two gripping devices 17 and 19 have a common vertical symmetry plane 35, which is unmovable relative to the carriage 14 and which contains the connecting line 38 between the gripping devices and which consequently is parallel to the sawing line 2. When the gripping arms 33 of the gripping devices 17 and 19 grasp the log 37 on the support beams 11 adjacent respectively the fore end and the rear end of the log, the log will obviously automatically be adjusted transversely so that a straight line through the centers of the two end surfaces of the log becomes parallel to the sawing line 2 through the sawing unit 1.

The middle gripping device 18, shown in FIG. 5, has on the contrary its yoke 32 pivoted in the associated carriage 20 about a horizontal axis 39 which coincides with the connecting line 38 between the outer gripping devices 17 and 19 and which consequently is located in the common vertical symmetry plane 35 of the two outer gripping devices 17 and 19. It is obvious that the middle gripping device 18 will be swung about the axis 39 transversely from the vertical plane 35 in response to any curve or bow in the log 37 that is grasped by the gripping devices. The sense and magnitude of the pivotal displacement of the gripping device 18 will obviously correspond to the direction and height of the curve in the log at the point along the log in which the gripping device 18 grasps the log.

The pivoting yoke 32 of the middle gripping device 18 is provided with a toothed segment 40 engaging a corresponding toothed segment 41 joumalled in the carriage 20 carrying the gripping device 18. The toothed segments 40 and 41 have the same diameter, whereby the toothed segment 41 is rotated through an angle equal to the pivot angle of the gripping device 18 relative to the vertical symmetry plane 35 but in the opposite sense. The toothed segment 41 is provided with an upwards pointing lever 42, which is vertical when the gripping device 18 is not pivoted from the vertical symmetry plane 35, that is,when the log 37 is straight. The lever 42 has such a length that the distance between the upper end of the lever and the axis of rotation of the segment 4l is substantially onehalf of the distance between the axis of rotation 39 of the yoke 32 and the lowermost ends of the gripping arms 33 coacting with the log 37. When, due to a curve or bow in the log 37,the gripping device 18 pivots transversely from the vertical symmetry plane 35, the upper end of the lever 42 is displaced transversely from its vertical neutral position through a distance corresponding to one-half of the height of the bow in the log 37 and in the same direction as the bow in the log.

The carriage 14 carrying the gripping devices 17, 18 and 19 can be moved along the horizontal girders 16, which are perpendicular to the sawing line 2 through the saw unit 1, by means of a motor 43 (see FIG. 3), which through a gear unit 44 rotates a shaft 45 which is coupled to the carriage 14 through crank rods 46 and connecting rods 47.

When the log 37 resting on the support beams 11 close to the discharge end of the transverse conveyor 9 has been grasped by the gripping devices 17, 18 and 19 in the way described in the foregoing, the driving motor 43 for the carriage 14 is started either automatically or manually by an attendant, whereby the carriage 14 with the gripping devices is moved transversely towards the input conveyor 4 for the sawingA unit l, that is to the left in FIG. 5. In this movement the gripping devices will bring along the log 37 supported by the support beams l l. A limit switch 49 is stationarily mounted in the vertical plane 48 through the sawing line 2 of the sawing unit 1 in such a way as to be actuated by the upper end of the lever 42 in the log adjusting device. This limit switch 49 is connected to the control circuits for the driving motor 43 in such manner that the driving motor 43 and thus also the movement of the carriage 14 and the transverse displacement of the log 37 grasped by the gripping devices is stopped when the switch 49 is actuated by the upper end of the lever 42. As the upper end of the lever 42 assumes, as described in the foregoing, a position relative to the vertical symmetry plane 35 through the log adjusting device which is determined by the direction and the magnitude of any curve or bow in the log 37, the log adjusting device will obviously be automatically stopped in such a position that a straight line through the centers of the end surfaces of the log 37 is parallel to the sawing line 2 of the saw unit l and transversely offset from the sawing line a distance corresponding to one-half of the height of the bow in the log 37 but in the direction opposite to the direction of the bow in the log. In this way the log 37 is automatically adjusted relative to the sawing line 2 through the sawing unit 1 with correct regard to and compensation for any bow in the log. t

When the log adjusting device and thus also the log 37 are stopped in the correct position, the gripping arms 33 in all the gripping devices 17, 18 and 19 are raised by means of the associated hydraulic cylinders 36 and at the same time the support beams 11 are loweredsomewhat, whereby the adjusted log 37 is put down onto the input conveyor 4, which will feed the log into the sawing unit 1 in the correct adjusted position for the log. Thereafter the motor 43 may be restarted automatically or manually in the opposite direction-so that the log adjusting device is returned to the position shown in FIG. 5 for receiving a new log supplied to the supporting beams l 1 by the transverse conveyor 9.

lt is obvious that the magnitude of the bow compensation may be chosen to any desired proportion of the height of the bow by variation of the length of the lever 42 or of the gear ratio between the two toothed segments 40 land 41. It is also obvious that it is not necessary to sense the magnitude of the bow at a point halfway between the ends of the log, as in the embodiment of the invention illustrated in the drawing and described in the foregoing, but that the bow can be sensed at any desired point along the log in that the middle gripping device 18 is arranged in a di`erent position between the two outer gripping devices 17 and 19. Thus for instance the maximum height of the bow is generally located somewhat closer to the root end than to the top end of the log, wherefore the gripping device 18 may be located somewhat closer to the outer gripping device 17 or 19 which adjusts the root end of the log. It should be noted that the transverse movement of the log adjusting device from the position in which it grasps the log to be adjusted and the correct adjusted position for the log above the input conveyor 4 of the sawing unit does not have to be as large as in the embodiment of the invention illustrated by way of example in the accompanying drawing and described in the foregoing. This embodiment of the invention has, however, the advantage that the log adjusting device can start the adjustment process for a new log already while the last adjusted log is fed into the sawing unit 1 by the conveyor 4. However, the final adjustment of the log is not carried out until in the position above the input conveyor 4 when the lever 42 strikes the limit switch 49 so that the movement of the log adjusting device is stopped.

' Ifthe bow indicating lever 42 is made sufficiently strong, the limit switch 49 may be replaced by a stationary mechanical limit stop, which stops the carriage 14 by cooperation with the lever 42. In this case the driving means for the carriage 14 should preferably include a slip coupling or a hydraulic driving motor, as for instance a hydraulic cylinder. It is also obvious that the carriage 14 can be replaced by two or several carriages, on which the gripping devices are mounted and which are driven or controlled in such a manner that the connecting line between the two outer gripping devices remains parallel to the vertical plane through the sawing line of the sawing unit and is moved transversely relative to this. If this condition is satisfied, it is,of course,not necessary that the girders 16 on which the carriage or system of carriages runs are completely horizontal or perpendicular to the sawing line.

It should also be obvious that if the lowermost end of the gripping arm 33 in any one of the gripping devices 17 18 and 19 comes to rest against a large knot on the log 37 to be adjusted, this will give cause to a faulty adjustment of the log, if no special precautions are taken. This disadvantage may be eliminated, however, if the lowermost ends of the gripping arms 33 are designed as schematically shown in FIGS. 6 and 7. The lowermost end of the gripping arm. 33 is in this case provided with two striking members 50 and 51 projecting from the gripping ann towards the log 37, which can be pressed into the arm against the action of springs 52. Only the spring 52 for the striking member 50 is visible in FIG. 6. The two striking members 50, 51 are mutually spaced in the longitudinal direction of the log 37 so that they will not simultaneously strike a knot on the log 37, as for instance the knot 53 in FIG. 7. A slidable interlocking plate 54 is coupled to the striking member 50 by means of a rod and a compression spring 56 mounted on the rod. The interlocking plate 54 is slidable in the gripping arm 33 transversely relative to the striking members 50 and 51. When the striking members 50 and 51 are unaffected, the interlocking plate 54 is located with its one end behind the striking member 50, whereas the other striking member 5l may be pressed into the gripping arm 33. If when the gripping ann 33 is moved towards a log 37 the striking member 5l strikes a knot 53 on the log 37, as illustrated to the left in FIG. 7, the striking member 51 is pressed into the gripping arm 33 and will lock the interlocking plate 54, whereby this prevent the other striking member 50 from being pressed into the gripping arm. In this way the gripping arm 33 will by means of the locked striking member 50 sense the actual position of the peripheral surface of the log 37. lf instead, as illustrated to the right in FIG. 7, the striking member S strikes a knot S7 on the log 37, this striking member 50 is pressed into the gripping arm 33, whereby the rod 55 and the compressor spring 56 displace the interlocking plate 54 transversely to a position in which the opposite end of the interlocking plate lies behind the other striking member S0 and locks it in its projecting position. In this case the gripping arm 30 will consequently by means of the striking member 51 locked in its projecting position sense the actual position of the peripheral surface of the log 37. It is obvious that various other interlocking mechanisms may be used for the two striking members 50 and 5l.

ln the embodiment of the invention illustrated by way of example in the accompanying drawings and described in the foregoing the log adjusting device is disposed above the log, but it should be obvious that it might also be disposed underneath the log with the gripping devices pointing upwards, as the log is supported by the support beams 1 l during the entire adjustment process and consequently does not need to be supported by the gripping device. ln the foregoing the invention has also been described in connection with a sawmill for cutting a log which has already been cut on two opposite sides. It should be obvious, however, that a similar adjusting device may also be used for adjusting completely fresh and untreated logs, boards to be edged or similar elongated items.

l claim: 1. Apparatus for aligning an elongate object, such as a log, to be sawn with a saw line at the input side of a sawmill having a plane of sawing containing said saw line, said object having an imaginary straight longitudinal center line extending through the centers of the opposite end surfaces thereof, said apparatus comprising:

object-positioning means for orienting said object so that said center line extends parallel to said saw line,

bow-sensing means for sensing the magnitude and direction of a bow in said object between said opposite end surfaces and in a direction normal to the plane of sawing,

bow-indicating means operable in response to sensings of said bow-sensing means to indicate the magnitude or a proportion of the magnitude of bow sensed and the direction of bow from said center line,

moving means for moving said object transversely toward said saw line while maintaining said center line parallel to said saw line,

and movement limiting means cooperable with said indicating means to stop said moving means when said center line is in a predetermined transverse position relative to said saw line as determined by the bow magnitude and directional indications of said indicating means.

2. Apparatus according to claim 1 wherein said bow-sensing means is movable longitudinally along an object to be sensed so as to be capable of sensing the magnitude and direction of bow in an object at various points along the length thereof.

3. Apparatus according to claim 1 wherein said bow-sensing means and said object-positioning means are carried by said moving means.

4. Apparatus according to claim 3 wherein said bow-indicating means is carried by said moving means and said limiting means is stationary relative to said moving means.

5. Apparatus according to claim 1 wherein said indicating means and said limiting means cooperate in a manner such that said moving means is stopped with said center line coincident with said sawing plane when said sensing means senses zero bow.

6. Apparatus according to claim 5 wherein said indicating means and said limiting means cooperate in a manner such that said moving means is stopped with said center line offset transversely of said sawing plane in a direction opposite the direction of bow when said sensing means senses a bow in said object.

7. Apparatus according to claim 6 wherein said indicating means and said limiting means cooperate to stop said moving means with said center line offset transversely of said sawing plane an amount corresponding to said predetermined proportion of the magnitude of bow indicated by said indicating means.

8. Apparatus according to claim 1 wherein said object-positioning means comprise first and second object-gripping devices mounted on said moving means and spaced from one another in the direction of said sawing line in a manner so as to maintain the center line of an object gripped thereby parallel to said sawing line and so that they are xed relative to said moving means in a direction normal to said plane of sawing.

9. Apparatus according to claim 8 wherein each of said first and second gripping devices includes two mutually and symmetrically movable gripping arms adapted to touch opposite sides of an object between them.

10. Apparatus according to claim 1 wherein said moving means includes a carriage means movable transversely of said saw line and mounting said positioning means, and driving means for moving said carriage means, said carriage means being mounted so that said center line remains substantially parallel to said saw line during said transverse movement.

l1. Apparatus according to claim 1 wherein said moving means includes a carriage means movable transversely of said saw line and said bow-sensing means comprises an objectgripping device mounted on said carriage means so as to be displaceable relative to said carriage means in a direction normal to a plane through said center line parallel to the plane of sawing.

12. Apparatus according to claim 1l wherein said objectgripping device includes two mutually and symmetrically movable gripping arms adapted to touch opposite sides of an object located between them and operable so that upon moving said arms into contact with opposite sides of said object at least a portion of said object-gripping device is displaced in a direction normal to said plane through said center line and in an amount corresponding to the magnitude of the bow at the point of contact.

13. Apparatus according to claim l1 wherein said objectgripping device upon contacting an object is displaceable relative to said plane through said center line an amount corresponding to the magnitude of the bow in said object where said gripping device contacts said object, said bow-indicating means including a member coupled to said gripping device and movable from a neutral position indicative of zero bow upon displacement of said gripping device in the same direction as that of said displacement and in magnitude a predetermined proportion of the displacement of said gripping device.

14. Apparatus according to claim 13 wherein said limiting means is stationarily mounted for coaction with said indicating member for stopping movement of said carriage means in a position determined by the position of said bow-indicating member relative to its neutral position, said limiting means being so located relative to said plane of sawing that said carriage means is stopped with said plane through said center line substantially coincident with said plane of sawing when said bow-indicating member is in its neutral position.

15. Apparatus according to claim 8 wherein said bowsensing means comprises a third gripping device mounted on said moving means between said first and second gripping devices and displaceable transversely relative to a plane through said center line parallel to said sawing plane, the magnitude of said displacement corresponding to the magnitude of the bow of an object where said third gripping device grips said object.

16. Apparatus according to claim 15 wherein each of said three gripping devices includes two mutually symmetrically movable gripping arms adapted to touch opposite sides of an object located between them.

17. At a sawmill a device at the input side of the sawmill for adjusting an elongated item to be sawn, as for instance a log,

relative to the sawing line through the sawmill with regard to v each gripping device including two mutually symmetrically movable gripping arms adapted to touch opposite sides of an item located between them,

said first and second gripping devices being mounted on said carriage means spacedv from each other in the direction of said sawing line so that the connecting line between them is parallel to said sawing line and so that they are unmovable relative to said carriage means in the direction perpendicular to the vertical plane through said connecting line, v

said third gripping device being located between said rst and second gripping devices and being mounted on said carriage means in the direction perpendicular to said ver tical plane,

a bow-indicating member being mounted on said carriage 'l means so as to be movable relative to a neutral position in a direction substantially perpendicular to said vertical plane and being coupled to said third gripping device so that its displacement from its neutral position is in a sense identical to and in magnitude a predetermined proportion of the displacement of said third gripping device from said vertical plane,

said carriage means being movable so that said vertical plane through said connecting line between said Erst and second gripping devices remains substantially parallel to the vertical plane through said sawing line buts moved transversely in the direction perpendicular to said latter vertical plane,

a driving means for moving said carriage means,

and stationary limit means arranged to coact with said bowindicating member for stopping said carriage means in a position determined by the pdsition of said bow-indicating member relative to its neutral position,

said limit means being so located relative to the vertical plane through the sawing line that said carriage means is stopped with the vertical plane through the connecting line between said first and said second gripping devices substantially coinciding with the vertical plane through the sawing line when said bow-indicating member is in its 4 neutral position.

18. A device as claimed in claim 17, wherein said stationary limit means include an electric limit switch inserted in an electric control system for said driving means for said carriage means to stop said driving means and thus the movement of said carriage means when actuated by said bow-indicating member.

19. A device as claimed in claim 17, wherein said third gripping device is located substantially halfway between said rst and said second gripping devices.

20. A device as claimed in claim 17, wherein said second and third gripping devices can be moved relative to said first gripping device in the direction parallel to said sawing line for adjustment of the position of the gripping devices to the length ofthe item to be sawn.

21. A device as claimed in claim 17, wherein said third gripping device is pivoted about a horizontal axis located in the vertical plane through said connecting line between said first and second gripping devices and said bow-indicating member consists of a lever, which is vertical in its said neutral position and is pivoted about a horizontal axis located in said vertical plane, the outer end of said lever being adapted to cooperate with said stationary limit means, which is located in the vertical plane containing said sawing line.

22. A device as claimed in claim 2l, wherein said bow-indicating lever is coupled to said third gripping device so as to be pivoted about its pivot axis through an angle corresponding to .the pivot angle of said third gripping device about its pivot axis, and the length of said bow-indicating lever between its pivot axis and its outer end corresponds substantially to onehalf of the distance between the pivot axis of said third gripping device and the portions of the gripping arms of said gripping device touching an item to be sawn.

23. A device as claimed in claim 17, comprising substantially horizontal support means for supporting an item to be sawn when grasped by said gripping devices.

24. A device as claimed in claim 17, comprising stationary, substantially horizontal tracks extending above said sawing line and supporting said carriage means, said gripping devices being dependent from said carriage means.

25. A device as claimed in claim 17, wherein each gripping arm is provided with two striking members projecting from the arm for striking the peripheral surface of an item to be sawn, said striking members being spaced from each other in the longitudinal direction of said item and resiliently impressable into the gripping arm, and interlocking means responsive to the impression of one of said striking members for locking the other striking member in its projecting position. 

1. Apparatus for aligning an elongate object, such as a log, to be sawn with a saw line at the input side of a sawmill having a plane of sawing containing said saw line, said object having an imaginary straight longitudinal center line extending through the centers of the opposite end surfaces thereof, said apparatus comprising: object-positioning means for orienting said object so that said center line extends parallel to said saw line, bow-sensing means for sensing the magnitude and direction of a bow in said object between said opposite end surfaces and in a direction normal to the plane of sawing, bow-indicating means operable in response to sensings of said bow-sensing means to indicate the magnitude or a proportion of the magnitude of bow sensed and the direction of bow from said center line, moving means for moving said object transversely toward said saw line while maintaining said center line parallel to said saw line, and movement limiting means cooperable with said indicating means to stop said moving means when said center line is in a predetermined transverse position relative to said saw line as determined by the bow magnitude and directional indications of said indicating means.
 2. Apparatus according to claim 1 wherein said bow-sensing means is movable longitudinally along an object to be sensed so as to be capable of sensing the magnitude and direction of bow in an object at various points along the length thereof.
 3. Apparatus according to claim 1 wherein said bow-sensing means and said object-positioning means are carried by said moving means.
 4. Apparatus according to claim 3 wherein said bow-indicating means is carried by said moving means and said limiting means is stationary relative to said moving means.
 5. Apparatus according to claim 1 wherein said indicating means and said limiting means cooperate in a manner such that said moving means is stopped with said center line coincident with said sawing plane when said sensing means senses zero bow.
 6. Apparatus according to claim 5 wherein said indicating means and said limiting means cooperate in a manner such that said moving means is stopped with said center line offset transversely of said sawing plane in a direction opposite the direction of bow when said sensing means senses a bow in said object.
 7. Apparatus according to claim 6 wherein said indicating means and said limiting means cooperate to stop said moving means with said center line offset transversely of said sawing plane an amount corresponding to said predetermined proportion of the magnitude of bow indicated by said indicating means.
 8. Apparatus according to claim 1 wherein said object-positioning means comprise first and second object-gripping devices mounted on said moVing means and spaced from one another in the direction of said sawing line in a manner so as to maintain the center line of an object gripped thereby parallel to said sawing line and so that they are fixed relative to said moving means in a direction normal to said plane of sawing.
 9. Apparatus according to claim 8 wherein each of said first and second gripping devices includes two mutually and symmetrically movable gripping arms adapted to touch opposite sides of an object between them.
 10. Apparatus according to claim 1 wherein said moving means includes a carriage means movable transversely of said saw line and mounting said positioning means, and driving means for moving said carriage means, said carriage means being mounted so that said center line remains substantially parallel to said saw line during said transverse movement.
 11. Apparatus according to claim 1 wherein said moving means includes a carriage means movable transversely of said saw line and said bow-sensing means comprises an object-gripping device mounted on said carriage means so as to be displaceable relative to said carriage means in a direction normal to a plane through said center line parallel to the plane of sawing.
 12. Apparatus according to claim 11 wherein said object-gripping device includes two mutually and symmetrically movable gripping arms adapted to touch opposite sides of an object located between them and operable so that upon moving said arms into contact with opposite sides of said object at least a portion of said object-gripping device is displaced in a direction normal to said plane through said center line and in an amount corresponding to the magnitude of the bow at the point of contact.
 13. Apparatus according to claim 11 wherein said object-gripping device upon contacting an object is displaceable relative to said plane through said center line an amount corresponding to the magnitude of the bow in said object where said gripping device contacts said object, said bow-indicating means including a member coupled to said gripping device and movable from a neutral position indicative of zero bow upon displacement of said gripping device in the same direction as that of said displacement and in magnitude a predetermined proportion of the displacement of said gripping device.
 14. Apparatus according to claim 13 wherein said limiting means is stationarily mounted for coaction with said indicating member for stopping movement of said carriage means in a position determined by the position of said bow-indicating member relative to its neutral position, said limiting means being so located relative to said plane of sawing that said carriage means is stopped with said plane through said center line substantially coincident with said plane of sawing when said bow-indicating member is in its neutral position.
 15. Apparatus according to claim 8 wherein said bow-sensing means comprises a third gripping device mounted on said moving means between said first and second gripping devices and displaceable transversely relative to a plane through said center line parallel to said sawing plane, the magnitude of said displacement corresponding to the magnitude of the bow of an object where said third gripping device grips said object.
 16. Apparatus according to claim 15 wherein each of said three gripping devices includes two mutually symmetrically movable gripping arms adapted to touch opposite sides of an object located between them.
 17. At a sawmill a device at the input side of the sawmill for adjusting an elongated item to be sawn, as for instance a log, relative to the sawing line through the sawmill with regard to any bow in said item, comprising: a first, a second and a third gripping device, carriage means carrying said gripping devices, each gripping device including two mutually symmetrically movable gripping arms adapted to touch opposite sides of an item located between them, said first and second gripping devices being mounted on said carriAge means spaced from each other in the direction of said sawing line so that the connecting line between them is parallel to said sawing line and so that they are unmovable relative to said carriage means in the direction perpendicular to the vertical plane through said connecting line, said third gripping device being located between said first and second gripping devices and being mounted on said carriage means in the direction perpendicular to said vertical plane, a bow-indicating member being mounted on said carriage means so as to be movable relative to a neutral position in a direction substantially perpendicular to said vertical plane and being coupled to said third gripping device so that its displacement from its neutral position is in a sense identical to and in magnitude a predetermined proportion of the displacement of said third gripping device from said vertical plane, said carriage means being movable so that said vertical plane through said connecting line between said first and second gripping devices remains substantially parallel to the vertical plane through said sawing line but is moved transversely in the direction perpendicular to said latter vertical plane, a driving means for moving said carriage means, and stationary limit means arranged to coact with said bow-indicating member for stopping said carriage means in a position determined by the position of said bow-indicating member relative to its neutral position, said limit means being so located relative to the vertical plane through the sawing line that said carriage means is stopped with the vertical plane through the connecting line between said first and said second gripping devices substantially coinciding with the vertical plane through the sawing line when said bow-indicating member is in its neutral position.
 18. A device as claimed in claim 17, wherein said stationary limit means include an electric limit switch inserted in an electric control system for said driving means for said carriage means to stop said driving means and thus the movement of said carriage means when actuated by said bow-indicating member.
 19. A device as claimed in claim 17, wherein said third gripping device is located substantially halfway between said first and said second gripping devices.
 20. A device as claimed in claim 17, wherein said second and third gripping devices can be moved relative to said first gripping device in the direction parallel to said sawing line for adjustment of the position of the gripping devices to the length of the item to be sawn.
 21. A device as claimed in claim 17, wherein said third gripping device is pivoted about a horizontal axis located in the vertical plane through said connecting line between said first and second gripping devices and said bow-indicating member consists of a lever, which is vertical in its said neutral position and is pivoted about a horizontal axis located in said vertical plane, the outer end of said lever being adapted to cooperate with said stationary limit means, which is located in the vertical plane containing said sawing line.
 22. A device as claimed in claim 21, wherein said bow-indicating lever is coupled to said third gripping device so as to be pivoted about its pivot axis through an angle corresponding to the pivot angle of said third gripping device about its pivot axis, and the length of said bow-indicating lever between its pivot axis and its outer end corresponds substantially to one-half of the distance between the pivot axis of said third gripping device and the portions of the gripping arms of said gripping device touching an item to be sawn.
 23. A device as claimed in claim 17, comprising substantially horizontal support means for supporting an item to be sawn when grasped by said gripping devices.
 24. A device as claimed in claim 17, comprising stationary, substantially horizontal tracks extending above said sawing line and supporting said carriage means, said gripping devices being dependent From said carriage means.
 25. A device as claimed in claim 17, wherein each gripping arm is provided with two striking members projecting from the arm for striking the peripheral surface of an item to be sawn, said striking members being spaced from each other in the longitudinal direction of said item and resiliently impressable into the gripping arm, and interlocking means responsive to the impression of one of said striking members for locking the other striking member in its projecting position. 